The present invention relates generally to Internet Protocol (IP) based telecommunications networks (IP networks) and, more specifically, to the redirection of traffic data between entry subnets of an IP network to arrive at an efficient signal path for carrying voice, data or video between a base station interface and any other network node using the IP network as the transport mechanism.
As the use of wireless communications networks has grown, so have the number and types of services and features available to the Amobile@ or wireless user. Such services and features have placed additional demands on the network and its resources as well as the service providers which operate and maintain the network. For example, there were more than 50 million mobile phone subscribers in the U.S. alone at the end of 1997, and the number of mobile phone subscribers is growing at an estimated annual rate of about 50%. In addition, the growing number and availability of mobile station features (such as caller ID, call blocking, and mobile phone location services) place heavier processing burdens on the existing network infrastructure.
Service providers are finding it challenging to keep pace with these increasing network demands. Accordingly, as more subscribers simultaneously make calls and use more mobile station features, networks become congested. A result of network congestion is that calls to and from mobile stations sometimes do not go through, and existing calls risk disconnection.
To lower the probability of service disruptions, service providers are increasing network capacity. One way of increasing network capacity is by purchasing more network hardware from an existing vendor. However, new network hardware that is compatible with the existing network architecture may not be available, or may be prohibitively expensive. Furthermore, network hardware from a new vendor is often difficult to integrate with existing network hardware. To overcome the issues of cost, compatibility, and to provide for future network growth, service providers are utilizing Internet Protocol (IP) networks as the transport mechanism to provide additional capacity and to accommodate future network demands.
An IP-based network can provide a multi-purpose transport mechanism for all sorts of data types including voice, video or data (collectively called Atraffic@). Moreover, the widespread use of IP makes it an ideal platform for integration of other communication platforms such as, for example, the Public Switched Telephone Network (PSTN) or other network types. For example, a base station interface could be configured as the gateway or interface between other components of the wireless network and an IP network. Likewise, a public network interface could provide the interface mechanism between the IP network and data originating in the PSTN.
Furthermore, within the IP network, subnets function as exchange mechanisms, for example, between the base station interface node and the public network interface node. Traffic monitoring functions in the IP network are typically concentrated, in an Operations and Maintenance (OandM) function. Other functions, such as call placement, handshaking, connection supervision and monitoring are accomplished through a system control interface.
In operation, when a voice call is made from a mobile station in the wireless network, the call reaches a base station via radio waves and is routed to a gateway which acts as the interface between the base station interface and the IP network . Additionally, the gateway functions to format the call into data packets suitable for transport over that IP network. The call enters one of a plurality of subnets and is directed to other nodes leading to elements of the PSTN, or another base station interface node, for example.
An advantage of IP networks is that they provide widely understood, predefined standards for transporting information data types including voice and video data. IP is said to be an Aopen@ (meaning non-proprietary) standard. Furthermore, since IP networks are non-proprietary, then benefit from a large number of installed hardware platforms. For these reasons, IP networks are becoming a popular choice for expanding existing network computing resources.
IP networks send each packet individually across the network nodes with the IP packet re-assembled at a destination point. During times of heavy traffic and network congestion, packets are sometimes lost, corrupted, or arrive out of order. The result is an increased probability that data will be lost or that transmission speeds are decreased during periods of high traffic. If the TCP/IP protocol is being used, a request for retransmission of lost or corrupted packets is generated, further increasing congestion levels on the network. The integrity of media information (e.g., computer data) is jeopardized whenever 100% of the packets don=t arrive 100% intact. While some levels of voice packet or video packet transfer failures are acceptable large number of retransmits can seriously jeopardize packet integrity and result in complete data loss.
While a retransmission algorithm can be used to recover lost packets, the increased overhead of such algorithms places an extra burden on scarce network resources and increases network congestion levels while at the same time decreasing capacity, and increasing delay and jitter.
When an IP network is used as a transport mechanism, voice, video, and data is introduced at a specified subnet of the IP network even though multiple subnets are available for packet transport that would ensure proper routing of the data to its intended destination while at the same time decrease congestion levels at specific subnets. By default, however, many IP interfaces introduce data at a predetermined subnet regardless of traffic conditions.
Therefore, what is needed is a method and system for managing the transfer of voice, video, and other data types through an IP network that minimizes network congestion. A solution that allows a network to determine a best subnet route for carrying voice, data or video between a base station interface and any other node in a reconfigured IP network would provide numerous advantages.
The present invention provides a method and system of decreasing congestion levels in an IP network used as a data transport mechanism that utilizes entry subnets to achieve load leveling. A system control interface analyzes network congestion information based on traffic data gathered by an operations and maintenance node and other data gathering devices, and, based on the indicated congestion conditions, a preferred subnet is selected as a pathway for all or part of an existing data stream or as a pathway for a new data stream.
According to one embodiment, disclosed is a method of controlling traffic over multiple IP subnets. The method comprises the steps of gathering traffic data associated with the multiple IP subnets and analyzing the traffic data to determine which of the multiple IP subnets provides the most appropriate connection for transmitting a data stream between the base station interface node of the wireless network and other nodes, for achieving a desired traffic distribution over the multiple IP subnets. The other nodes may include a second base station interface node, a public network node, a gateway node to a different network, or any other similar node.
The method may include the steps of introducing a data stream from the base station interface node onto a first subnet, and then directing a new data stream (or redirecting an existing data stream) through a second subnet. The step of analysis may use statistical decision theory to analyze traffic data when selecting a preferred subnet. For example, one may use statistical theory to decide when a subnet is congested, before re-routing traffic to a different subnet. The data stream may include voice packets, video packets, or data packets.
A data stream may flow across more than two subnets of the IP network. Accordingly, a first data stream portion may be directed between the base station interface and the other node via a first subnet, and a second data stream portion may be directed between the base station interface and the other node via a second subnet, and so on.
The method of the present invention can be applied where a voice data stream initiated by a phone call over a wireless network consists of voice (or audio) packets introduced into the IP network from the base station interface node. It may also consist of traffic that is routed from an IP network to the base station interface for transmission over the air interface. Thus, several phone calls can be directed across a first subnet as a plurality of voice data streams. Then, some or all these voice data streams, or a voice data stream initiated by a new call, may be routed between the base station interface node and a second node through a second subnet.
In another embodiment, disclosed is a method of relieving IP network congestion in a data communications system. The system comprises an IP network for carrying traffic between a base station interface and a node within the IP network. The method comprises the steps of gathering data associated with a first subnet and a second subnet of the IP network and analyzing the data in order to select either the first subnet or the second subnet as a preferred subnet. Next, data traffic is directed between the base station interface and the second network node via the preferred subnet.
Also disclosed is a system for controlling traffic over multiple IP subnets (control system interface) of an IP network in a communications system comprising a wireless network and an IP network configured as a transport mechanism between the wireless network and other nodes connected to the IP network. In one embodiment, a PSTN interface is provided as a gateway between the IP network and the PSTN. The base station interface node functions as the gateway between the IP network and the wireless network. The control system comprises at least two subnets in communication with the base station interface, an operation and maintenance interface for gathering traffic data associated with the multiple IP subnets, and a system control interface for analyzing the traffic data to determine which of the multiple IP subnets provides the most appropriate connection for transmitting the data stream between the base station interface and the other network node for achieving a desired traffic distribution over the multiple IP subnets.